DESCRIPTION: The intent of this application is to focus on the continued development of novel glass and glass-ceramic (hydroxyapatite) coatings for metallic and ceramic implants. Our long term goal is to produce "smart" bioactive coatings with excellent adhesion to the substrate and long term stability. Implant materials represent an extreme challenge since they must satisfy many conflicting requirements. Indeed, as no single material can meet all these requirements, the use of coatings becomes essential. Such coatings represent further material challenges in that they require bonding to the substrate without compromising their primary functional properties. Our research has shown that the most advantageous strategy to overcome this challenge is to design functionally graded (FGM) glass and glass-ceramic coatings. This is a significant improvement over current commercial coating techniques such as plasma spraying, where the control of the coating composition and microstructure is severely limited. The graded design can also be extended for the fabrication of bioactive coatings providing local delivery platform for growth factors and drugs, to encourage positive and specific interactions between the coatings and their cellular and tissue environment and to deliver therapeutic agents. Nevertheless, in order to achieve this objective novel coating techniques and glass compositions need to be developed. The Specific Aims of this grant continuation are: 1) To test the hypothesis that novel glass systems can be developed for the fabrication of controlled graded coatings on diverse materials using different processing techniques; 2) To test the hypothesis that novel coating techniques can be combined to prepare graded coatings with structural and compositional control over micro to nano size-scales; 3) To test the hypothesis that alumina-zirconia nanocomposites have adequate mechanical properties, specifically strength, toughness and fatigue resistance, to be used for Dental applications and further that the coating techniques developed can be extended for use with ceramic structural materials; and 4) To test the hypothesis that in an animal model, bone-implant contact and bonding can be markedly enhanced for implants with graded coatings versus uncoated controls. The combination of novel materials and processing techniques with systematic mechanical and biological evaluation will allow us to develop a new family of coatings with an unprecedented (but necessary) level of microstructural control, optimized surface morphologies and controlled dissolution behavior. These coatings will be adaptable to a wide range of applications permitting much improved biointegration of implants.